Tim Nicholls introduces himself to a worker at an engineering company in Brisbane on Saturday.
Photograph: Dan Peled/AAP

The gloves are officially off in the Queensland election campaign as it approaches its final week, with Tim Nicholls breaking from his positive campaign strategy to call Annastacia Palaszczuk “a liar”.

Nicholls, the former treasurer in the LNP government, has spent the majority of the last three weeks campaigning on a platform of positivity, as he seeks to distance himself from lingering misgivings over his role in the unpopular Newman government.

But as a sceptical Queensland electorate struggles to make up its mind between the two major parties, while One Nation looms as the game changer, Nicholls has dropped the positivity a week out from polling day to attack his rival.

“Let’s take a look about her lie about paying down the state’s debt, it is now going to go up to $81bn. Let’s have a look at her lie about keeping her cabinet at a small number and she has increased it,” he said from Brisbane’s outer north suburbs.

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“Let’s have a look at her lie about changing the voting reforms and introducing compulsory preferential voting for political advantage.

“And let’s look at her lie about the secret deals that she alleges the LNP or other people have engaged in and let’s have a look at the lie where she said there will be no secret deals to subsidise the Carmichael mine and there is a secret royalties deal she is failing to release.

“There have been lies galore and quite frankly, I think people think it is dumb.”

Labor changed Queensland’s voting system to compulsory preferential by amending an LNP bill to increase the number of electorates. It has shifted debt from the bottom line on to government-owned corporations, while it has agreed to a royalties holiday with Adani, but maintains all monies will be paid back, with interest.

Labor had previously seized on the LNP preference deal, announced a week ago, which has One Nation directly preferenced above Labor in 50 of the 61 seats it is running in, and on Friday, it jumped on Nicholls’s admission he would work with One Nation if necessary.

“There is a clear choice, a fundamental clear choice that they have to make, and it is whether they want good, decent, sound government, or do they want the chaos of the LNP and One Nation,” Palaszcuk said on Saturday.

“And let’s be clear, a deal has been done between Tim Nicholls and One Nation. This is a recipe for chaos.”

Nicholls denies a deal has been done.

“She has made ludicrous claims about LNP smear campaigns with no evidence,” he said, in reference to Palaszczuk’s veto of the Adani rail line loan.

“She has made ludicrous claims about deals with no evidence. She has made claims that there will be no secret deals in relation to the Carmichael mine and she has done a secret deal and won’t release it. They are clearly mistruths and lies by Annastacia Palaszczuk. It is a question of trust and she can’t be trusted.”

Nicholls, who last came to power under the promise that “public servants have nothing to fear” and then oversaw 14,000 job losses in a mass slashing of the public service, said he had learnt from his “mistakes”.

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“I have done my absolute best to always uphold my word to the people of Queensland and when I have made mistakes, I have stood up and admitted to it, and said I have made my mistakes,” he said.

He denied that the preference deal, followed by the acknowledgment that the LNP would work with One Nation if necessary, had given voters permission to vote for the outlier party.

“I have been very frank with the people of Queensland. I am not going to pull the wool over your eyes like Annastacia Palaszczuk. I am not going to pretend that the people of Queensland don’t have a right to cast their vote in the way that they want to. I will deal with the parliament that the Queensland people elect,” he said.

“I am not going to hold a gun to people’s heads as Annastacia Palaszczuk is doing and says ‘oh well, if I don’t like it, we are going to go back to the polls time and time again’.”

A spokesman for Palaszczuk said Nicholls’ comments were ‘bizarre’. “Tim Nicholls can’t give straight answers. His deal with One Nation is in black and white for all Queenslanders to see. It’s his deal,” he said.

Queensland goes to the polls on 25 November. Both parties will officially launch their campaigns on Sunday.